Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "classfile/classLoader.hpp"

 #include "classfile/javaClasses.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "classfile/vmSymbols.hpp"

 #include "code/scopeDesc.hpp"

 #include "compiler/compileBroker.hpp"

 #include "interpreter/interpreter.hpp"

 #include "interpreter/linkResolver.hpp"

 #include "interpreter/oopMapCache.hpp"

 #include "jvmtifiles/jvmtiEnv.hpp"

 #include "memory/oopFactory.hpp"

 #include "memory/universe.inline.hpp"

 #include "oops/instanceKlass.hpp"

 #include "oops/objArrayOop.hpp"

 #include "oops/oop.inline.hpp"

 #include "oops/symbol.hpp"

 #include "prims/jvm_misc.hpp"

 #include "prims/jvmtiExport.hpp"

 #include "prims/jvmtiThreadState.hpp"

 #include "prims/privilegedStack.hpp"

 #include "runtime/aprofiler.hpp"

 #include "runtime/arguments.hpp"

 #include "runtime/biasedLocking.hpp"

 #include "runtime/deoptimization.hpp"

 #include "runtime/fprofiler.hpp"

 #include "runtime/frame.inline.hpp"

 #include "runtime/init.hpp"

 #include "runtime/interfaceSupport.hpp"

 #include "runtime/java.hpp"

 #include "runtime/javaCalls.hpp"

 #include "runtime/jniPeriodicChecker.hpp"

 #include "runtime/memprofiler.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "runtime/objectMonitor.hpp"

 #include "runtime/osThread.hpp"

 #include "runtime/safepoint.hpp"

 #include "runtime/sharedRuntime.hpp"

 #include "runtime/statSampler.hpp"

 #include "runtime/stubRoutines.hpp"

 #include "runtime/task.hpp"

 #include "runtime/threadCritical.hpp"

 #include "runtime/threadLocalStorage.hpp"

 #include "runtime/vframe.hpp"

 #include "runtime/vframeArray.hpp"

 #include "runtime/vframe_hp.hpp"

 #include "runtime/vmThread.hpp"

 #include "runtime/vm_operations.hpp"

 #include "services/attachListener.hpp"

 #include "services/management.hpp"

 #include "services/threadService.hpp"

 #include "utilities/defaultStream.hpp"

 #include "utilities/dtrace.hpp"

 #include "utilities/events.hpp"

 #include "utilities/preserveException.hpp"

 #ifdef TARGET_OS_FAMILY_linux

 # include "os_linux.inline.hpp"

 # include "thread_linux.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_solaris

 # include "os_solaris.inline.hpp"

 # include "thread_solaris.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_windows

 # include "os_windows.inline.hpp"

 # include "thread_windows.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_bsd

 # include "os_bsd.inline.hpp"

 # include "thread_bsd.inline.hpp"

 #endif

 #ifndef SERIALGC

 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"

 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"

 #include "gc_implementation/parallelScavenge/pcTasks.hpp"

 #endif

 #ifdef COMPILER1

 #include "c1/c1_Compiler.hpp"

 #endif

 #ifdef COMPILER2

 #include "opto/c2compiler.hpp"

 #include "opto/idealGraphPrinter.hpp"

 #endif

 #ifdef DTRACE_ENABLED

 // Only bother with this argument setup if dtrace is available

 #ifndef USDT2

 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin);

 HS_DTRACE_PROBE_DECL(hotspot, vm__init__end);

 HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t,

   intptr_t, intptr_t, bool);

 HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t,

   intptr_t, intptr_t, bool);

 #define DTRACE_THREAD_PROBE(probe, javathread)                             \

   {                                                                        \

     ResourceMark rm(this);                                                 \

     int len = 0;                                                           \

     const char* name = (javathread)->get_thread_name();                    \

     len = strlen(name);                                                    \

     HS_DTRACE_PROBE5(hotspot, thread__##probe,                             \

       name, len,                                                           \

       java_lang_Thread::thread_id((javathread)->threadObj()),              \

       (javathread)->osthread()->thread_id(),                               \

       java_lang_Thread::is_daemon((javathread)->threadObj()));             \

   }

 #else /* USDT2 */

 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START

 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP

 #define DTRACE_THREAD_PROBE(probe, javathread)                             \

   {                                                                        \

     ResourceMark rm(this);                                                 \

     int len = 0;                                                           \

     const char* name = (javathread)->get_thread_name();                    \

     len = strlen(name);                                                    \

     HOTSPOT_THREAD_PROBE_##probe(  /* probe = start, stop */               \

       (char *) name, len,                                                           \

       java_lang_Thread::thread_id((javathread)->threadObj()),              \

       (uintptr_t) (javathread)->osthread()->thread_id(),                               \

       java_lang_Thread::is_daemon((javathread)->threadObj()));             \

   }

 #endif /* USDT2 */

 #else //  ndef DTRACE_ENABLED

 #define DTRACE_THREAD_PROBE(probe, javathread)

 #endif // ndef DTRACE_ENABLED

 // Class hierarchy

 // - Thread

 //   - VMThread

 //   - WatcherThread

 //   - ConcurrentMarkSweepThread

 //   - JavaThread

 //     - CompilerThread

 // ======= Thread ========

 // Support for forcing alignment of thread objects for biased locking

 void* Thread::operator new(size_t size) {

   if (UseBiasedLocking) {

     const int alignment = markOopDesc::biased_lock_alignment;

     size_t aligned_size = size + (alignment - sizeof(intptr_t));

     void* real_malloc_addr = CHeapObj::operator new(aligned_size);

     void* aligned_addr     = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);

     assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=

            ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),

            "JavaThread alignment code overflowed allocated storage");

     if (TraceBiasedLocking) {

       if (aligned_addr != real_malloc_addr)

         tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,

                       real_malloc_addr, aligned_addr);

     }

     ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;

     return aligned_addr;

   } else {

     return CHeapObj::operator new(size);

   }

 }

 void Thread::operator delete(void* p) {

   if (UseBiasedLocking) {

     void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;

     CHeapObj::operator delete(real_malloc_addr);

   } else {

     CHeapObj::operator delete(p);

   }

 }

 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,

 // JavaThread

 Thread::Thread() {

   // stack and get_thread

   set_stack_base(NULL);

   set_stack_size(0);

   set_self_raw_id(0);

   set_lgrp_id(-1);

   // allocated data structures

   set_osthread(NULL);

   set_resource_area(new ResourceArea());

   set_handle_area(new HandleArea(NULL));

   set_active_handles(NULL);

   set_free_handle_block(NULL);

   set_last_handle_mark(NULL);

   // This initial value ==> never claimed.

   _oops_do_parity = 0;

   // the handle mark links itself to last_handle_mark

   new HandleMark(this);

   // plain initialization

   debug_only(_owned_locks = NULL;)

   debug_only(_allow_allocation_count = 0;)

   NOT_PRODUCT(_allow_safepoint_count = 0;)

   NOT_PRODUCT(_skip_gcalot = false;)

   CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;)

   _jvmti_env_iteration_count = 0;

   set_allocated_bytes(0);

   _vm_operation_started_count = 0;

   _vm_operation_completed_count = 0;

   _current_pending_monitor = NULL;

   _current_pending_monitor_is_from_java = true;

   _current_waiting_monitor = NULL;

   _num_nested_signal = 0;

   omFreeList = NULL ;

   omFreeCount = 0 ;

   omFreeProvision = 32 ;

   omInUseList = NULL ;

   omInUseCount = 0 ;

   _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true);

   _suspend_flags = 0;

   // thread-specific hashCode stream generator state - Marsaglia shift-xor form

   _hashStateX = os::random() ;

   _hashStateY = 842502087 ;

   _hashStateZ = 0x8767 ;    // (int)(3579807591LL & 0xffff) ;

   _hashStateW = 273326509 ;

   _OnTrap   = 0 ;

   _schedctl = NULL ;

   _Stalled  = 0 ;

   _TypeTag  = 0x2BAD ;

   // Many of the following fields are effectively final - immutable

   // Note that nascent threads can't use the Native Monitor-Mutex

   // construct until the _MutexEvent is initialized ...

   // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents

   // we might instead use a stack of ParkEvents that we could provision on-demand.

   // The stack would act as a cache to avoid calls to ParkEvent::Allocate()

   // and ::Release()

   _ParkEvent   = ParkEvent::Allocate (this) ;

   _SleepEvent  = ParkEvent::Allocate (this) ;

   _MutexEvent  = ParkEvent::Allocate (this) ;

   _MuxEvent    = ParkEvent::Allocate (this) ;

 #ifdef CHECK_UNHANDLED_OOPS

   if (CheckUnhandledOops) {

     _unhandled_oops = new UnhandledOops(this);

   }

 #endif // CHECK_UNHANDLED_OOPS

 #ifdef ASSERT

   if (UseBiasedLocking) {

     assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");

     assert(this == _real_malloc_address ||

            this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),

            "bug in forced alignment of thread objects");

   }

 #endif /* ASSERT */

 }

 void Thread::initialize_thread_local_storage() {

   // Note: Make sure this method only calls

   // non-blocking operations. Otherwise, it might not work

   // with the thread-startup/safepoint interaction.

   // During Java thread startup, safepoint code should allow this

   // method to complete because it may need to allocate memory to

   // store information for the new thread.

   // initialize structure dependent on thread local storage

   ThreadLocalStorage::set_thread(this);

   // set up any platform-specific state.

   os::initialize_thread();

 }

 void Thread::record_stack_base_and_size() {

   set_stack_base(os::current_stack_base());

   set_stack_size(os::current_stack_size());

 }

 Thread::~Thread() {

   // Reclaim the objectmonitors from the omFreeList of the moribund thread.

   ObjectSynchronizer::omFlush (this) ;

   // deallocate data structures

   delete resource_area();

   // since the handle marks are using the handle area, we have to deallocated the root

   // handle mark before deallocating the thread's handle area,

   assert(last_handle_mark() != NULL, "check we have an element");

   delete last_handle_mark();

   assert(last_handle_mark() == NULL, "check we have reached the end");

   // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.

   // We NULL out the fields for good hygiene.

   ParkEvent::Release (_ParkEvent)   ; _ParkEvent   = NULL ;

   ParkEvent::Release (_SleepEvent)  ; _SleepEvent  = NULL ;

   ParkEvent::Release (_MutexEvent)  ; _MutexEvent  = NULL ;

   ParkEvent::Release (_MuxEvent)    ; _MuxEvent    = NULL ;

   delete handle_area();

   // osthread() can be NULL, if creation of thread failed.

   if (osthread() != NULL) os::free_thread(osthread());

   delete _SR_lock;

   // clear thread local storage if the Thread is deleting itself

   if (this == Thread::current()) {

     ThreadLocalStorage::set_thread(NULL);

   } else {

     // In the case where we're not the current thread, invalidate all the

     // caches in case some code tries to get the current thread or the

     // thread that was destroyed, and gets stale information.

     ThreadLocalStorage::invalidate_all();

   }

   CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)

 }

 // NOTE: dummy function for assertion purpose.

 void Thread::run() {

   ShouldNotReachHere();

 }

 #ifdef ASSERT

 // Private method to check for dangling thread pointer

 void check_for_dangling_thread_pointer(Thread *thread) {

  assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),

          "possibility of dangling Thread pointer");

 }

 #endif

 #ifndef PRODUCT

 // Tracing method for basic thread operations

 void Thread::trace(const char* msg, const Thread* const thread) {

   if (!TraceThreadEvents) return;

   ResourceMark rm;

   ThreadCritical tc;

   const char *name = "non-Java thread";

   int prio = -1;

   if (thread->is_Java_thread()

       && !thread->is_Compiler_thread()) {

     // The Threads_lock must be held to get information about

     // this thread but may not be in some situations when

     // tracing  thread events.

     bool release_Threads_lock = false;

     if (!Threads_lock->owned_by_self()) {

       Threads_lock->lock();

       release_Threads_lock = true;

     }

     JavaThread* jt = (JavaThread *)thread;

     name = (char *)jt->get_thread_name();

     oop thread_oop = jt->threadObj();

     if (thread_oop != NULL) {

       prio = java_lang_Thread::priority(thread_oop);

     }

     if (release_Threads_lock) {

       Threads_lock->unlock();

     }

   }

   tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio);

 }

 #endif

 ThreadPriority Thread::get_priority(const Thread* const thread) {

   trace("get priority", thread);

   ThreadPriority priority;

   // Can return an error!

   (void)os::get_priority(thread, priority);

   assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");

   return priority;

 }

 void Thread::set_priority(Thread* thread, ThreadPriority priority) {

   trace("set priority", thread);

   debug_only(check_for_dangling_thread_pointer(thread);)

   // Can return an error!

   (void)os::set_priority(thread, priority);

 }

 void Thread::start(Thread* thread) {

   trace("start", thread);

   // Start is different from resume in that its safety is guaranteed by context or

   // being called from a Java method synchronized on the Thread object.

   if (!DisableStartThread) {

     if (thread->is_Java_thread()) {

       // Initialize the thread state to RUNNABLE before starting this thread.

       // Can not set it after the thread started because we do not know the

       // exact thread state at that time. It could be in MONITOR_WAIT or

       // in SLEEPING or some other state.

       java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),

                                           java_lang_Thread::RUNNABLE);

     }

     os::start_thread(thread);

   }

 }

 // Enqueue a VM_Operation to do the job for us - sometime later

 void Thread::send_async_exception(oop java_thread, oop java_throwable) {

   VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);

   VMThread::execute(vm_stop);

 }

 //

 // Check if an external suspend request has completed (or has been

 // cancelled). Returns true if the thread is externally suspended and

 // false otherwise.

 //

 // The bits parameter returns information about the code path through

 // the routine. Useful for debugging:

 //

 // set in is_ext_suspend_completed():

 // 0x00000001 - routine was entered

 // 0x00000010 - routine return false at end

 // 0x00000100 - thread exited (return false)

 // 0x00000200 - suspend request cancelled (return false)

 // 0x00000400 - thread suspended (return true)

 // 0x00001000 - thread is in a suspend equivalent state (return true)

 // 0x00002000 - thread is native and walkable (return true)

 // 0x00004000 - thread is native_trans and walkable (needed retry)

 //

 // set in wait_for_ext_suspend_completion():

 // 0x00010000 - routine was entered

 // 0x00020000 - suspend request cancelled before loop (return false)

 // 0x00040000 - thread suspended before loop (return true)

 // 0x00080000 - suspend request cancelled in loop (return false)

 // 0x00100000 - thread suspended in loop (return true)

 // 0x00200000 - suspend not completed during retry loop (return false)

 //

 // Helper class for tracing suspend wait debug bits.

 //

 // 0x00000100 indicates that the target thread exited before it could

 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and

 // 0x00080000 each indicate a cancelled suspend request so they don't

 // count as wait failures either.

 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)

 class TraceSuspendDebugBits : public StackObj {

  private:

   JavaThread * jt;

   bool         is_wait;

   bool         called_by_wait;  // meaningful when !is_wait

   uint32_t *   bits;

  public:

   TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,

                         uint32_t *_bits) {

     jt             = _jt;

     is_wait        = _is_wait;

     called_by_wait = _called_by_wait;

     bits           = _bits;

   }

   ~TraceSuspendDebugBits() {

     if (!is_wait) {

 #if 1

       // By default, don't trace bits for is_ext_suspend_completed() calls.

       // That trace is very chatty.

       return;

 #else

       if (!called_by_wait) {

         // If tracing for is_ext_suspend_completed() is enabled, then only

         // trace calls to it from wait_for_ext_suspend_completion()

         return;

       }

 #endif

     }

     if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {

       if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {

         MutexLocker ml(Threads_lock);  // needed for get_thread_name()

         ResourceMark rm;

         tty->print_cr(

             "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",

             jt->get_thread_name(), *bits);

         guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");

       }

     }

   }

 };

 #undef DEBUG_FALSE_BITS

 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) {

   TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);

   bool did_trans_retry = false;  // only do thread_in_native_trans retry once

   bool do_trans_retry;           // flag to force the retry

   *bits |= 0x00000001;

   do {

     do_trans_retry = false;

     if (is_exiting()) {

       // Thread is in the process of exiting. This is always checked

       // first to reduce the risk of dereferencing a freed JavaThread.

       *bits |= 0x00000100;

       return false;

     }

     if (!is_external_suspend()) {

       // Suspend request is cancelled. This is always checked before

       // is_ext_suspended() to reduce the risk of a rogue resume

       // confusing the thread that made the suspend request.

       *bits |= 0x00000200;

       return false;

     }

     if (is_ext_suspended()) {

       // thread is suspended

       *bits |= 0x00000400;

       return true;

     }

     // Now that we no longer do hard suspends of threads running

     // native code, the target thread can be changing thread state

     // while we are in this routine:

     //

     //   _thread_in_native -> _thread_in_native_trans -> _thread_blocked

     //

     // We save a copy of the thread state as observed at this moment

     // and make our decision about suspend completeness based on the

     // copy. This closes the race where the thread state is seen as

     // _thread_in_native_trans in the if-thread_blocked check, but is

     // seen as _thread_blocked in if-thread_in_native_trans check.

     JavaThreadState save_state = thread_state();

     if (save_state == _thread_blocked && is_suspend_equivalent()) {

       // If the thread's state is _thread_blocked and this blocking

       // condition is known to be equivalent to a suspend, then we can

       // consider the thread to be externally suspended. This means that

       // the code that sets _thread_blocked has been modified to do

       // self-suspension if the blocking condition releases. We also

       // used to check for CONDVAR_WAIT here, but that is now covered by

       // the _thread_blocked with self-suspension check.

       //

       // Return true since we wouldn't be here unless there was still an

       // external suspend request.

       *bits |= 0x00001000;

       return true;

     } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {

       // Threads running native code will self-suspend on native==>VM/Java

       // transitions. If its stack is walkable (should always be the case

       // unless this function is called before the actual java_suspend()

       // call), then the wait is done.

       *bits |= 0x00002000;

       return true;

     } else if (!called_by_wait && !did_trans_retry &&

                save_state == _thread_in_native_trans &&

                frame_anchor()->walkable()) {

       // The thread is transitioning from thread_in_native to another

       // thread state. check_safepoint_and_suspend_for_native_trans()

       // will force the thread to self-suspend. If it hasn't gotten

       // there yet we may have caught the thread in-between the native

       // code check above and the self-suspend. Lucky us. If we were

       // called by wait_for_ext_suspend_completion(), then it

       // will be doing the retries so we don't have to.

       //

       // Since we use the saved thread state in the if-statement above,

       // there is a chance that the thread has already transitioned to

       // _thread_blocked by the time we get here. In that case, we will

       // make a single unnecessary pass through the logic below. This

       // doesn't hurt anything since we still do the trans retry.

       *bits |= 0x00004000;

       // Once the thread leaves thread_in_native_trans for another

       // thread state, we break out of this retry loop. We shouldn't

       // need this flag to prevent us from getting back here, but

       // sometimes paranoia is good.

       did_trans_retry = true;

       // We wait for the thread to transition to a more usable state.

       for (int i = 1; i <= SuspendRetryCount; i++) {

         // We used to do an "os::yield_all(i)" call here with the intention

         // that yielding would increase on each retry. However, the parameter

         // is ignored on Linux which means the yield didn't scale up. Waiting

         // on the SR_lock below provides a much more predictable scale up for

         // the delay. It also provides a simple/direct point to check for any

         // safepoint requests from the VMThread

         // temporarily drops SR_lock while doing wait with safepoint check

         // (if we're a JavaThread - the WatcherThread can also call this)

         // and increase delay with each retry

         SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);

         // check the actual thread state instead of what we saved above

         if (thread_state() != _thread_in_native_trans) {

           // the thread has transitioned to another thread state so

           // try all the checks (except this one) one more time.

           do_trans_retry = true;

           break;

         }

       } // end retry loop

     }

   } while (do_trans_retry);

   *bits |= 0x00000010;

   return false;

 }

 //

 // Wait for an external suspend request to complete (or be cancelled).

 // Returns true if the thread is externally suspended and false otherwise.

 //

 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,

        uint32_t *bits) {

   TraceSuspendDebugBits tsdb(this, true /* is_wait */,

                              false /* !called_by_wait */, bits);

   // local flag copies to minimize SR_lock hold time

   bool is_suspended;

   bool pending;

   uint32_t reset_bits;

   // set a marker so is_ext_suspend_completed() knows we are the caller

   *bits |= 0x00010000;

   // We use reset_bits to reinitialize the bits value at the top of

   // each retry loop. This allows the caller to make use of any

   // unused bits for their own marking purposes.

   reset_bits = *bits;

   {

     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);

     is_suspended = is_ext_suspend_completed(true /* called_by_wait */,

                                             delay, bits);

     pending = is_external_suspend();

   }

   // must release SR_lock to allow suspension to complete

   if (!pending) {

     // A cancelled suspend request is the only false return from

     // is_ext_suspend_completed() that keeps us from entering the

     // retry loop.

     *bits |= 0x00020000;

     return false;

   }

   if (is_suspended) {

     *bits |= 0x00040000;

     return true;

   }

   for (int i = 1; i <= retries; i++) {

     *bits = reset_bits;  // reinit to only track last retry

     // We used to do an "os::yield_all(i)" call here with the intention

     // that yielding would increase on each retry. However, the parameter

     // is ignored on Linux which means the yield didn't scale up. Waiting

     // on the SR_lock below provides a much more predictable scale up for

     // the delay. It also provides a simple/direct point to check for any

     // safepoint requests from the VMThread

     {

       MutexLocker ml(SR_lock());

       // wait with safepoint check (if we're a JavaThread - the WatcherThread

       // can also call this)  and increase delay with each retry

       SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);

       is_suspended = is_ext_suspend_completed(true /* called_by_wait */,

                                               delay, bits);

       // It is possible for the external suspend request to be cancelled

       // (by a resume) before the actual suspend operation is completed.

       // Refresh our local copy to see if we still need to wait.

       pending = is_external_suspend();

     }

     if (!pending) {

       // A cancelled suspend request is the only false return from

       // is_ext_suspend_completed() that keeps us from staying in the

       // retry loop.

       *bits |= 0x00080000;

       return false;

     }

     if (is_suspended) {

       *bits |= 0x00100000;

       return true;

     }

   } // end retry loop

   // thread did not suspend after all our retries

   *bits |= 0x00200000;

   return false;

 }

 #ifndef PRODUCT

 void JavaThread::record_jump(address target, address instr, const char* file, int line) {

   // This should not need to be atomic as the only way for simultaneous

   // updates is via interrupts. Even then this should be rare or non-existant

   // and we don't care that much anyway.

   int index = _jmp_ring_index;

   _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1);

   _jmp_ring[index]._target = (intptr_t) target;

   _jmp_ring[index]._instruction = (intptr_t) instr;

   _jmp_ring[index]._file = file;

   _jmp_ring[index]._line = line;

 }

 #endif /* PRODUCT */

 // Called by flat profiler

 // Callers have already called wait_for_ext_suspend_completion

 // The assertion for that is currently too complex to put here:

 bool JavaThread::profile_last_Java_frame(frame* _fr) {

   bool gotframe = false;

   // self suspension saves needed state.

   if (has_last_Java_frame() && _anchor.walkable()) {

      *_fr = pd_last_frame();

      gotframe = true;

   }

   return gotframe;

 }

 void Thread::interrupt(Thread* thread) {

   trace("interrupt", thread);

   debug_only(check_for_dangling_thread_pointer(thread);)

   os::interrupt(thread);

 }

 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {

   trace("is_interrupted", thread);

   debug_only(check_for_dangling_thread_pointer(thread);)

   // Note:  If clear_interrupted==false, this simply fetches and

   // returns the value of the field osthread()->interrupted().

   return os::is_interrupted(thread, clear_interrupted);

 }

 // GC Support

 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {

   jint thread_parity = _oops_do_parity;

   if (thread_parity != strong_roots_parity) {

     jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);

     if (res == thread_parity) {

       return true;

     } else {

       guarantee(res == strong_roots_parity, "Or else what?");

       assert(SharedHeap::heap()->workers()->active_workers() > 0,

          "Should only fail when parallel.");

       return false;

     }

   }

   assert(SharedHeap::heap()->workers()->active_workers() > 0,

          "Should only fail when parallel.");

   return false;

 }

 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) {

   active_handles()->oops_do(f);

   // Do oop for ThreadShadow

   f->do_oop((oop*)&_pending_exception);

   handle_area()->oops_do(f);

 }

 void Thread::nmethods_do(CodeBlobClosure* cf) {

   // no nmethods in a generic thread...

 }

 void Thread::print_on(outputStream* st) const {

   // get_priority assumes osthread initialized

   if (osthread() != NULL) {

     st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this);

     osthread()->print_on(st);

   }

   debug_only(if (WizardMode) print_owned_locks_on(st);)

 }

 // Thread::print_on_error() is called by fatal error handler. Don't use

 // any lock or allocate memory.

 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {

   if      (is_VM_thread())                  st->print("VMThread");

   else if (is_Compiler_thread())            st->print("CompilerThread");

   else if (is_Java_thread())                st->print("JavaThread");

   else if (is_GC_task_thread())             st->print("GCTaskThread");

   else if (is_Watcher_thread())             st->print("WatcherThread");

   else if (is_ConcurrentGC_thread())        st->print("ConcurrentGCThread");

   else st->print("Thread");

   st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",

             _stack_base - _stack_size, _stack_base);

   if (osthread()) {

     st->print(" [id=%d]", osthread()->thread_id());

   }

 }

 #ifdef ASSERT

 void Thread::print_owned_locks_on(outputStream* st) const {

   Monitor *cur = _owned_locks;

   if (cur == NULL) {

     st->print(" (no locks) ");

   } else {

     st->print_cr(" Locks owned:");

     while(cur) {

       cur->print_on(st);

       cur = cur->next();

     }

   }

 }

 static int ref_use_count  = 0;

 bool Thread::owns_locks_but_compiled_lock() const {

   for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {

     if (cur != Compile_lock) return true;

   }

   return false;

 }

 #endif

 #ifndef PRODUCT

 // The flag: potential_vm_operation notifies if this particular safepoint state could potential

 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that

 // no threads which allow_vm_block's are held

 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {

     // Check if current thread is allowed to block at a safepoint

     if (!(_allow_safepoint_count == 0))

       fatal("Possible safepoint reached by thread that does not allow it");

     if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {

       fatal("LEAF method calling lock?");

     }

 #ifdef ASSERT

     if (potential_vm_operation && is_Java_thread()

         && !Universe::is_bootstrapping()) {

       // Make sure we do not hold any locks that the VM thread also uses.

       // This could potentially lead to deadlocks

       for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {

         // Threads_lock is special, since the safepoint synchronization will not start before this is

         // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,

         // since it is used to transfer control between JavaThreads and the VMThread

         // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first!

         if ( (cur->allow_vm_block() &&

               cur != Threads_lock &&

               cur != Compile_lock &&               // Temporary: should not be necessary when we get spearate compilation

               cur != VMOperationRequest_lock &&

               cur != VMOperationQueue_lock) ||

               cur->rank() == Mutex::special) {

           warning("Thread holding lock at safepoint that vm can block on: %s", cur->name());

         }

       }

     }

     if (GCALotAtAllSafepoints) {

       // We could enter a safepoint here and thus have a gc

       InterfaceSupport::check_gc_alot();

     }

 #endif

 }

 #endif

 bool Thread::is_in_stack(address adr) const {

   assert(Thread::current() == this, "is_in_stack can only be called from current thread");

   address end = os::current_stack_pointer();

   if (stack_base() >= adr && adr >= end) return true;

   return false;

 }

 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter

 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being

 // used for compilation in the future. If that change is made, the need for these methods

 // should be revisited, and they should be removed if possible.

 bool Thread::is_lock_owned(address adr) const {

   return on_local_stack(adr);

 }

 bool Thread::set_as_starting_thread() {

  // NOTE: this must be called inside the main thread.

   return os::create_main_thread((JavaThread*)this);

 }

 static void initialize_class(Symbol* class_name, TRAPS) {

   klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);

   instanceKlass::cast(klass)->initialize(CHECK);

 }

 // Creates the initial ThreadGroup

 static Handle create_initial_thread_group(TRAPS) {

   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);

   instanceKlassHandle klass (THREAD, k);

   Handle system_instance = klass->allocate_instance_handle(CHECK_NH);

   {

     JavaValue result(T_VOID);

     JavaCalls::call_special(&result,

                             system_instance,

                             klass,

                             vmSymbols::object_initializer_name(),

                             vmSymbols::void_method_signature(),

                             CHECK_NH);

   }

   Universe::set_system_thread_group(system_instance());

   Handle main_instance = klass->allocate_instance_handle(CHECK_NH);

   {

     JavaValue result(T_VOID);

     Handle string = java_lang_String::create_from_str("main", CHECK_NH);

     JavaCalls::call_special(&result,

                             main_instance,

                             klass,

                             vmSymbols::object_initializer_name(),

                             vmSymbols::threadgroup_string_void_signature(),

                             system_instance,

                             string,

                             CHECK_NH);

   }

   return main_instance;

 }

 // Creates the initial Thread

 static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) {

   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);

   instanceKlassHandle klass (THREAD, k);

   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);

   java_lang_Thread::set_thread(thread_oop(), thread);

   java_lang_Thread::set_priority(thread_oop(), NormPriority);

   thread->set_threadObj(thread_oop());

   Handle string = java_lang_String::create_from_str("main", CHECK_NULL);

   JavaValue result(T_VOID);

   JavaCalls::call_special(&result, thread_oop,

                                    klass,

                                    vmSymbols::object_initializer_name(),

                                    vmSymbols::threadgroup_string_void_signature(),

                                    thread_group,

                                    string,

                                    CHECK_NULL);

   return thread_oop();

 }

 static void call_initializeSystemClass(TRAPS) {

   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);

   instanceKlassHandle klass (THREAD, k);

   JavaValue result(T_VOID);

   JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),

                                          vmSymbols::void_method_signature(), CHECK);

 }

 // General purpose hook into Java code, run once when the VM is initialized.

 // The Java library method itself may be changed independently from the VM.

 static void call_postVMInitHook(TRAPS) {

   klassOop k = SystemDictionary::PostVMInitHook_klass();

   instanceKlassHandle klass (THREAD, k);

   if (klass.not_null()) {

     JavaValue result(T_VOID);

     JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),

                                            vmSymbols::void_method_signature(),

                                            CHECK);

   }

 }

 static void reset_vm_info_property(TRAPS) {

   // the vm info string

   ResourceMark rm(THREAD);

   const char *vm_info = VM_Version::vm_info_string();

   // java.lang.System class

   klassOop k =  SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);

   instanceKlassHandle klass (THREAD, k);

   // setProperty arguments

   Handle key_str    = java_lang_String::create_from_str("java.vm.info", CHECK);

   Handle value_str  = java_lang_String::create_from_str(vm_info, CHECK);

   // return value

   JavaValue r(T_OBJECT);

   // public static String setProperty(String key, String value);

   JavaCalls::call_static(&r,

                          klass,

                          vmSymbols::setProperty_name(),

                          vmSymbols::string_string_string_signature(),

                          key_str,

                          value_str,

                          CHECK);

 }

 void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) {

   assert(thread_group.not_null(), "thread group should be specified");

   assert(threadObj() == NULL, "should only create Java thread object once");

   klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);

   instanceKlassHandle klass (THREAD, k);

   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);

   java_lang_Thread::set_thread(thread_oop(), this);

   java_lang_Thread::set_priority(thread_oop(), NormPriority);

   set_threadObj(thread_oop());

   JavaValue result(T_VOID);

   if (thread_name != NULL) {

     Handle name = java_lang_String::create_from_str(thread_name, CHECK);

     // Thread gets assigned specified name and null target

     JavaCalls::call_special(&result,

                             thread_oop,

                             klass,

                             vmSymbols::object_initializer_name(),

                             vmSymbols::threadgroup_string_void_signature(),

                             thread_group, // Argument 1

                             name,         // Argument 2

                             THREAD);

   } else {

     // Thread gets assigned name "Thread-nnn" and null target

     // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)

     JavaCalls::call_special(&result,

                             thread_oop,

                             klass,

                             vmSymbols::object_initializer_name(),

                             vmSymbols::threadgroup_runnable_void_signature(),

                             thread_group, // Argument 1

                             Handle(),     // Argument 2

                             THREAD);

   }

   if (daemon) {

       java_lang_Thread::set_daemon(thread_oop());

   }

   if (HAS_PENDING_EXCEPTION) {

     return;

   }

   KlassHandle group(this, SystemDictionary::ThreadGroup_klass());

   Handle threadObj(this, this->threadObj());

   JavaCalls::call_special(&result,

                          thread_group,

                          group,

                          vmSymbols::add_method_name(),

                          vmSymbols::thread_void_signature(),

                          threadObj,          // Arg 1

                          THREAD);

 }

 // NamedThread --  non-JavaThread subclasses with multiple

 // uniquely named instances should derive from this.

 NamedThread::NamedThread() : Thread() {

   _name = NULL;

   _processed_thread = NULL;

 }

 NamedThread::~NamedThread() {

   if (_name != NULL) {

     FREE_C_HEAP_ARRAY(char, _name);

     _name = NULL;

   }

 }

 void NamedThread::set_name(const char* format, ...) {

   guarantee(_name == NULL, "Only get to set name once.");

   _name = NEW_C_HEAP_ARRAY(char, max_name_len);

   guarantee(_name != NULL, "alloc failure");

   va_list ap;

   va_start(ap, format);

   jio_vsnprintf(_name, max_name_len, format, ap);

   va_end(ap);

 }

 // ======= WatcherThread ========

 // The watcher thread exists to simulate timer interrupts.  It should

 // be replaced by an abstraction over whatever native support for

 // timer interrupts exists on the platform.

 WatcherThread* WatcherThread::_watcher_thread   = NULL;

 volatile bool  WatcherThread::_should_terminate = false;

 WatcherThread::WatcherThread() : Thread() {

   assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");

   if (os::create_thread(this, os::watcher_thread)) {

     _watcher_thread = this;

     // Set the watcher thread to the highest OS priority which should not be

     // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY

     // is created. The only normal thread using this priority is the reference

     // handler thread, which runs for very short intervals only.

     // If the VMThread's priority is not lower than the WatcherThread profiling

     // will be inaccurate.

     os::set_priority(this, MaxPriority);

     if (!DisableStartThread) {

       os::start_thread(this);

     }

   }

 }

 void WatcherThread::run() {

   assert(this == watcher_thread(), "just checking");

   this->record_stack_base_and_size();

   this->initialize_thread_local_storage();

   this->set_active_handles(JNIHandleBlock::allocate_block());

   while(!_should_terminate) {

     assert(watcher_thread() == Thread::current(),  "thread consistency check");

     assert(watcher_thread() == this,  "thread consistency check");

     // Calculate how long it'll be until the next PeriodicTask work

     // should be done, and sleep that amount of time.

     size_t time_to_wait = PeriodicTask::time_to_wait();

     // we expect this to timeout - we only ever get unparked when

     // we should terminate

     {

       OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);

       jlong prev_time = os::javaTimeNanos();

       for (;;) {

         int res= _SleepEvent->park(time_to_wait);

         if (res == OS_TIMEOUT || _should_terminate)

           break;

         // spurious wakeup of some kind

         jlong now = os::javaTimeNanos();

         time_to_wait -= (now - prev_time) / 1000000;

         if (time_to_wait <= 0)

           break;

         prev_time = now;

       }

     }

     if (is_error_reported()) {

       // A fatal error has happened, the error handler(VMError::report_and_die)

       // should abort JVM after creating an error log file. However in some

       // rare cases, the error handler itself might deadlock. Here we try to

       // kill JVM if the fatal error handler fails to abort in 2 minutes.

       //

       // This code is in WatcherThread because WatcherThread wakes up

       // periodically so the fatal error handler doesn't need to do anything;

       // also because the WatcherThread is less likely to crash than other

       // threads.

       for (;;) {

         if (!ShowMessageBoxOnError

          && (OnError == NULL || OnError[0] == '\0')

          && Arguments::abort_hook() == NULL) {

              os::sleep(this, 2 * 60 * 1000, false);

              fdStream err(defaultStream::output_fd());

              err.print_raw_cr("# [ timer expired, abort... ]");

              // skip atexit/vm_exit/vm_abort hooks

              os::die();

         }

         // Wake up 5 seconds later, the fatal handler may reset OnError or

         // ShowMessageBoxOnError when it is ready to abort.

         os::sleep(this, 5 * 1000, false);

       }

     }

     PeriodicTask::real_time_tick(time_to_wait);

     // If we have no more tasks left due to dynamic disenrollment,

     // shut down the thread since we don't currently support dynamic enrollment

     if (PeriodicTask::num_tasks() == 0) {

       _should_terminate = true;

     }

   }

   // Signal that it is terminated

   {

     MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);

     _watcher_thread = NULL;

     Terminator_lock->notify();

   }

   // Thread destructor usually does this..

   ThreadLocalStorage::set_thread(NULL);

 }

 void WatcherThread::start() {

   if (watcher_thread() == NULL) {

     _should_terminate = false;

     // Create the single instance of WatcherThread

     new WatcherThread();

   }

 }

 void WatcherThread::stop() {

   // it is ok to take late safepoints here, if needed

   MutexLocker mu(Terminator_lock);

   _should_terminate = true;

   OrderAccess::fence();  // ensure WatcherThread sees update in main loop

   Thread* watcher = watcher_thread();

   if (watcher != NULL)

     watcher->_SleepEvent->unpark();

   while(watcher_thread() != NULL) {

     // This wait should make safepoint checks, wait without a timeout,

     // and wait as a suspend-equivalent condition.

     //

     // Note: If the FlatProfiler is running, then this thread is waiting

     // for the WatcherThread to terminate and the WatcherThread, via the

     // FlatProfiler task, is waiting for the external suspend request on

     // this thread to complete. wait_for_ext_suspend_completion() will

     // eventually timeout, but that takes time. Making this wait a

     // suspend-equivalent condition solves that timeout problem.

     //

     Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,

                           Mutex::_as_suspend_equivalent_flag);

   }

 }

 void WatcherThread::print_on(outputStream* st) const {

   st->print("\"%s\" ", name());

   Thread::print_on(st);

   st->cr();

 }

 // ======= JavaThread ========

 // A JavaThread is a normal Java thread

 void JavaThread::initialize() {

   // Initialize fields

   // Set the claimed par_id to -1 (ie not claiming any par_ids)

   set_claimed_par_id(-1);

   set_saved_exception_pc(NULL);

   set_threadObj(NULL);

   _anchor.clear();

   set_entry_point(NULL);

   set_jni_functions(jni_functions());

   set_callee_target(NULL);

   set_vm_result(NULL);

   set_vm_result_2(NULL);

   set_vframe_array_head(NULL);

   set_vframe_array_last(NULL);

   set_deferred_locals(NULL);

   set_deopt_mark(NULL);

   set_deopt_nmethod(NULL);

   clear_must_deopt_id();

   set_monitor_chunks(NULL);

   set_next(NULL);

   set_thread_state(_thread_new);

   _terminated = _not_terminated;

   _privileged_stack_top = NULL;

   _array_for_gc = NULL;

   _suspend_equivalent = false;

   _in_deopt_handler = 0;

   _doing_unsafe_access = false;

   _stack_guard_state = stack_guard_unused;

   _exception_oop = NULL;

   _exception_pc  = 0;

   _exception_handler_pc = 0;

   _is_method_handle_return = 0;

   _jvmti_thread_state= NULL;

   _should_post_on_exceptions_flag = JNI_FALSE;

   _jvmti_get_loaded_classes_closure = NULL;

   _interp_only_mode    = 0;

   _special_runtime_exit_condition = _no_async_condition;

   _pending_async_exception = NULL;

   _is_compiling = false;

   _thread_stat = NULL;

   _thread_stat = new ThreadStatistics();

   _blocked_on_compilation = false;

   _jni_active_critical = 0;

   _do_not_unlock_if_synchronized = false;

   _cached_monitor_info = NULL;

   _parker = Parker::Allocate(this) ;

 #ifndef PRODUCT

   _jmp_ring_index = 0;

   for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) {

     record_jump(NULL, NULL, NULL, 0);

   }

 #endif /* PRODUCT */

   set_thread_profiler(NULL);

   if (FlatProfiler::is_active()) {

     // This is where we would decide to either give each thread it's own profiler

     // or use one global one from FlatProfiler,

     // or up to some count of the number of profiled threads, etc.

     ThreadProfiler* pp = new ThreadProfiler();

     pp->engage();

     set_thread_profiler(pp);

   }

   // Setup safepoint state info for this thread

   ThreadSafepointState::create(this);

   debug_only(_java_call_counter = 0);

   // JVMTI PopFrame support

   _popframe_condition = popframe_inactive;

   _popframe_preserved_args = NULL;

   _popframe_preserved_args_size = 0;

   pd_initialize();

 }

 #ifndef SERIALGC

 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;

 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;

 #endif // !SERIALGC

 JavaThread::JavaThread(bool is_attaching_via_jni) :

   Thread()

 #ifndef SERIALGC

   , _satb_mark_queue(&_satb_mark_queue_set),

   _dirty_card_queue(&_dirty_card_queue_set)

 #endif // !SERIALGC

 {

   initialize();

   if (is_attaching_via_jni) {

     _jni_attach_state = _attaching_via_jni;

   } else {

     _jni_attach_state = _not_attaching_via_jni;

   }

   assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor");

 }

 bool JavaThread::reguard_stack(address cur_sp) {

   if (_stack_guard_state != stack_guard_yellow_disabled) {

     return true; // Stack already guarded or guard pages not needed.

   }

   if (register_stack_overflow()) {

     // For those architectures which have separate register and

     // memory stacks, we must check the register stack to see if

     // it has overflowed.

     return false;

   }

   // Java code never executes within the yellow zone: the latter is only

   // there to provoke an exception during stack banging.  If java code

   // is executing there, either StackShadowPages should be larger, or

   // some exception code in c1, c2 or the interpreter isn't unwinding

   // when it should.

   guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");

   enable_stack_yellow_zone();

   return true;

 }

 bool JavaThread::reguard_stack(void) {

   return reguard_stack(os::current_stack_pointer());

 }

 void JavaThread::block_if_vm_exited() {

   if (_terminated == _vm_exited) {

     // _vm_exited is set at safepoint, and Threads_lock is never released

     // we will block here forever

     Threads_lock->lock_without_safepoint_check();

     ShouldNotReachHere();

   }

 }

 // Remove this ifdef when C1 is ported to the compiler interface.

 static void compiler_thread_entry(JavaThread* thread, TRAPS);

 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :

   Thread()

 #ifndef SERIALGC

   , _satb_mark_queue(&_satb_mark_queue_set),

   _dirty_card_queue(&_dirty_card_queue_set)

 #endif // !SERIALGC

 {

   if (TraceThreadEvents) {

     tty->print_cr("creating thread %p", this);

   }

   initialize();

   _jni_attach_state = _not_attaching_via_jni;

   set_entry_point(entry_point);

   // Create the native thread itself.

   // %note runtime_23

   os::ThreadType thr_type = os::java_thread;

   thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :

                                                      os::java_thread;

   os::create_thread(this, thr_type, stack_sz);

   // The _osthread may be NULL here because we ran out of memory (too many threads active).

   // We need to throw and OutOfMemoryError - however we cannot do this here because the caller

   // may hold a lock and all locks must be unlocked before throwing the exception (throwing

   // the exception consists of creating the exception object & initializing it, initialization

   // will leave the VM via a JavaCall and then all locks must be unlocked).

   //

   // The thread is still suspended when we reach here. Thread must be explicit started

   // by creator! Furthermore, the thread must also explicitly be added to the Threads list

   // by calling Threads:add. The reason why this is not done here, is because the thread

   // object must be fully initialized (take a look at JVM_Start)

 }

 JavaThread::~JavaThread() {

   if (TraceThreadEvents) {

       tty->print_cr("terminate thread %p", this);

   }

   // JSR166 -- return the parker to the free list

   Parker::Release(_parker);

   _parker = NULL ;

   // Free any remaining  previous UnrollBlock

   vframeArray* old_array = vframe_array_last();

   if (old_array != NULL) {

     Deoptimization::UnrollBlock* old_info = old_array->unroll_block();

     old_array->set_unroll_block(NULL);

     delete old_info;

     delete old_array;

   }

   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();

   if (deferred != NULL) {

     // This can only happen if thread is destroyed before deoptimization occurs.

     assert(deferred->length() != 0, "empty array!");

     do {

       jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);

       deferred->remove_at(0);

       // individual jvmtiDeferredLocalVariableSet are CHeapObj's

       delete dlv;

     } while (deferred->length() != 0);

     delete deferred;

   }

   // All Java related clean up happens in exit

   ThreadSafepointState::destroy(this);

   if (_thread_profiler != NULL) delete _thread_profiler;

   if (_thread_stat != NULL) delete _thread_stat;

 }

 // The first routine called by a new Java thread

 void JavaThread::run() {

   // initialize thread-local alloc buffer related fields

   this->initialize_tlab();

   // used to test validitity of stack trace backs

   this->record_base_of_stack_pointer();

   // Record real stack base and size.

   this->record_stack_base_and_size();

   // Initialize thread local storage; set before calling MutexLocker

   this->initialize_thread_local_storage();

   this->create_stack_guard_pages();

   this->cache_global_variables();

   // Thread is now sufficient initialized to be handled by the safepoint code as being

   // in the VM. Change thread state from _thread_new to _thread_in_vm

   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);

   assert(JavaThread::current() == this, "sanity check");

   assert(!Thread::current()->owns_locks(), "sanity check");

   DTRACE_THREAD_PROBE(start, this);

   // This operation might block. We call that after all safepoint checks for a new thread has

   // been completed.

   this->set_active_handles(JNIHandleBlock::allocate_block());

   if (JvmtiExport::should_post_thread_life()) {

     JvmtiExport::post_thread_start(this);

   }

   // We call another function to do the rest so we are sure that the stack addresses used

   // from there will be lower than the stack base just computed

   thread_main_inner();

   // Note, thread is no longer valid at this point!

 }

 void JavaThread::thread_main_inner() {

   assert(JavaThread::current() == this, "sanity check");

   assert(this->threadObj() != NULL, "just checking");

   // Execute thread entry point unless this thread has a pending exception

   // or has been stopped before starting.

   // Note: Due to JVM_StopThread we can have pending exceptions already!

   if (!this->has_pending_exception() &&

       !java_lang_Thread::is_stillborn(this->threadObj())) {

     {

       ResourceMark rm(this);

       this->set_native_thread_name(this->get_thread_name());

     }

     HandleMark hm(this);

     this->entry_point()(this, this);

   }

   DTRACE_THREAD_PROBE(stop, this);

   this->exit(false);

   delete this;

 }

 static void ensure_join(JavaThread* thread) {

   // We do not need to grap the Threads_lock, since we are operating on ourself.

   Handle threadObj(thread, thread->threadObj());

   assert(threadObj.not_null(), "java thread object must exist");

   ObjectLocker lock(threadObj, thread);

   // Ignore pending exception (ThreadDeath), since we are exiting anyway

   thread->clear_pending_exception();

   // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.

   java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);

   // Clear the native thread instance - this makes isAlive return false and allows the join()

   // to complete once we've done the notify_all below

   java_lang_Thread::set_thread(threadObj(), NULL);

   lock.notify_all(thread);

   // Ignore pending exception (ThreadDeath), since we are exiting anyway

   thread->clear_pending_exception();

 }

 // For any new cleanup additions, please check to see if they need to be applied to

 // cleanup_failed_attach_current_thread as well.

 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {

   assert(this == JavaThread::current(),  "thread consistency check");

   if (!InitializeJavaLangSystem) return;

   HandleMark hm(this);

   Handle uncaught_exception(this, this->pending_exception());

   this->clear_pending_exception();

   Handle threadObj(this, this->threadObj());

   assert(threadObj.not_null(), "Java thread object should be created");

   if (get_thread_profiler() != NULL) {

     get_thread_profiler()->disengage();

     ResourceMark rm;

     get_thread_profiler()->print(get_thread_name());

   }

   // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place

   {

     EXCEPTION_MARK;

     CLEAR_PENDING_EXCEPTION;

   }

   // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This

   // has to be fixed by a runtime query method

   if (!destroy_vm || JDK_Version::is_jdk12x_version()) {

     // JSR-166: change call from from ThreadGroup.uncaughtException to

     // java.lang.Thread.dispatchUncaughtException

     if (uncaught_exception.not_null()) {

       Handle group(this, java_lang_Thread::threadGroup(threadObj()));

       Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT",

         (address)uncaught_exception(), (address)threadObj(), (address)group());

       {

         EXCEPTION_MARK;

         // Check if the method Thread.dispatchUncaughtException() exists. If so

         // call it.  Otherwise we have an older library without the JSR-166 changes,

         // so call ThreadGroup.uncaughtException()

         KlassHandle recvrKlass(THREAD, threadObj->klass());

         CallInfo callinfo;

         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());

         LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass,

                                            vmSymbols::dispatchUncaughtException_name(),

                                            vmSymbols::throwable_void_signature(),

                                            KlassHandle(), false, false, THREAD);

         CLEAR_PENDING_EXCEPTION;

         methodHandle method = callinfo.selected_method();

         if (method.not_null()) {

           JavaValue result(T_VOID);

           JavaCalls::call_virtual(&result,

                                   threadObj, thread_klass,

                                   vmSymbols::dispatchUncaughtException_name(),

                                   vmSymbols::throwable_void_signature(),

                                   uncaught_exception,

                                   THREAD);

         } else {

           KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass());

           JavaValue result(T_VOID);

           JavaCalls::call_virtual(&result,

                                   group, thread_group,

                                   vmSymbols::uncaughtException_name(),

                                   vmSymbols::thread_throwable_void_signature(),

                                   threadObj,           // Arg 1

                                   uncaught_exception,  // Arg 2

                                   THREAD);

         }

         if (HAS_PENDING_EXCEPTION) {

           ResourceMark rm(this);

           jio_fprintf(defaultStream::error_stream(),

                 "\nException: %s thrown from the UncaughtExceptionHandler"

                 " in thread \"%s\"\n",

                 Klass::cast(pending_exception()->klass())->external_name(),

                 get_thread_name());

           CLEAR_PENDING_EXCEPTION;

         }

       }

     }

     // Call Thread.exit(). We try 3 times in case we got another Thread.stop during

     // the execution of the method. If that is not enough, then we don't really care. Thread.stop

     // is deprecated anyhow.

     { int count = 3;

       while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {

         EXCEPTION_MARK;

         JavaValue result(T_VOID);

         KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());

         JavaCalls::call_virtual(&result,

                               threadObj, thread_klass,

                               vmSymbols::exit_method_name(),

                               vmSymbols::void_method_signature(),

                               THREAD);

         CLEAR_PENDING_EXCEPTION;

       }

     }

     // notify JVMTI

     if (JvmtiExport::should_post_thread_life()) {

       JvmtiExport::post_thread_end(this);

     }

     // We have notified the agents that we are exiting, before we go on,

     // we must check for a pending external suspend request and honor it

     // in order to not surprise the thread that made the suspend request.

     while (true) {

       {

         MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);

         if (!is_external_suspend()) {

           set_terminated(_thread_exiting);

           ThreadService::current_thread_exiting(this);

           break;

         }

         // Implied else:

         // Things get a little tricky here. We have a pending external

         // suspend request, but we are holding the SR_lock so we

         // can't just self-suspend. So we temporarily drop the lock

         // and then self-suspend.

       }

       ThreadBlockInVM tbivm(this);

       java_suspend_self();

       // We're done with this suspend request, but we have to loop around

       // and check again. Eventually we will get SR_lock without a pending

       // external suspend request and will be able to mark ourselves as

       // exiting.

     }

     // no more external suspends are allowed at this point

   } else {

     // before_exit() has already posted JVMTI THREAD_END events

   }

   // Notify waiters on thread object. This has to be done after exit() is called

   // on the thread (if the thread is the last thread in a daemon ThreadGroup the

   // group should have the destroyed bit set before waiters are notified).

   ensure_join(this);

   assert(!this->has_pending_exception(), "ensure_join should have cleared");

   // 6282335 JNI DetachCurrentThread spec states that all Java monitors

   // held by this thread must be released.  A detach operation must only

   // get here if there are no Java frames on the stack.  Therefore, any

   // owned monitors at this point MUST be JNI-acquired monitors which are

   // pre-inflated and in the monitor cache.

   //

   // ensure_join() ignores IllegalThreadStateExceptions, and so does this.

   if (exit_type == jni_detach && JNIDetachReleasesMonitors) {

     assert(!this->has_last_Java_frame(), "detaching with Java frames?");

     ObjectSynchronizer::release_monitors_owned_by_thread(this);

     assert(!this->has_pending_exception(), "release_monitors should have cleared");

   }

   // These things needs to be done while we are still a Java Thread. Make sure that thread

   // is in a consistent state, in case GC happens

   assert(_privileged_stack_top == NULL, "must be NULL when we get here");

   if (active_handles() != NULL) {

     JNIHandleBlock* block = active_handles();

     set_active_handles(NULL);

     JNIHandleBlock::release_block(block);

   }

   if (free_handle_block() != NULL) {

     JNIHandleBlock* block = free_handle_block();

     set_free_handle_block(NULL);

     JNIHandleBlock::release_block(block);

   }

   // These have to be removed while this is still a valid thread.

   remove_stack_guard_pages();

   if (UseTLAB) {

     tlab().make_parsable(true);  // retire TLAB

   }

   if (JvmtiEnv::environments_might_exist()) {

     JvmtiExport::cleanup_thread(this);

   }

 #ifndef SERIALGC

   // We must flush G1-related buffers before removing a thread from

   // the list of active threads.

   if (UseG1GC) {

     flush_barrier_queues();

   }

 #endif

   // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread

   Threads::remove(this);

 }

 #ifndef SERIALGC

 // Flush G1-related queues.

 void JavaThread::flush_barrier_queues() {

   satb_mark_queue().flush();

   dirty_card_queue().flush();

 }

 void JavaThread::initialize_queues() {

   assert(!SafepointSynchronize::is_at_safepoint(),

          "we should not be at a safepoint");

   ObjPtrQueue& satb_queue = satb_mark_queue();

   SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();

   // The SATB queue should have been constructed with its active

   // field set to false.

   assert(!satb_queue.is_active(), "SATB queue should not be active");

   assert(satb_queue.is_empty(), "SATB queue should be empty");

   // If we are creating the thread during a marking cycle, we should

   // set the active field of the SATB queue to true.

   if (satb_queue_set.is_active()) {

     satb_queue.set_active(true);

   }

   DirtyCardQueue& dirty_queue = dirty_card_queue();

   // The dirty card queue should have been constructed with its

   // active field set to true.

   assert(dirty_queue.is_active(), "dirty card queue should be active");

 }

 #endif // !SERIALGC

 void JavaThread::cleanup_failed_attach_current_thread() {

   if (get_thread_profiler() != NULL) {

     get_thread_profiler()->disengage();

     ResourceMark rm;

     get_thread_profiler()->print(get_thread_name());

   }

   if (active_handles() != NULL) {

     JNIHandleBlock* block = active_handles();

     set_active_handles(NULL);

     JNIHandleBlock::release_block(block);

   }

   if (free_handle_block() != NULL) {

     JNIHandleBlock* block = free_handle_block();

     set_free_handle_block(NULL);

     JNIHandleBlock::release_block(block);

   }

   // These have to be removed while this is still a valid thread.

   remove_stack_guard_pages();

   if (UseTLAB) {

     tlab().make_parsable(true);  // retire TLAB, if any

   }

 #ifndef SERIALGC

   if (UseG1GC) {

     flush_barrier_queues();

   }

 #endif

   Threads::remove(this);

   delete this;

 }

 JavaThread* JavaThread::active() {

   Thread* thread = ThreadLocalStorage::thread();

   assert(thread != NULL, "just checking");

   if (thread->is_Java_thread()) {

     return (JavaThread*) thread;

   } else {

     assert(thread->is_VM_thread(), "this must be a vm thread");

     VM_Operation* op = ((VMThread*) thread)->vm_operation();

     JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();

     assert(ret->is_Java_thread(), "must be a Java thread");

     return ret;

   }

 }

 bool JavaThread::is_lock_owned(address adr) const {

   if (Thread::is_lock_owned(adr)) return true;

   for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {

     if (chunk->contains(adr)) return true;

   }

   return false;

 }

 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {

   chunk->set_next(monitor_chunks());

   set_monitor_chunks(chunk);

 }

 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {

   guarantee(monitor_chunks() != NULL, "must be non empty");

   if (monitor_chunks() == chunk) {

     set_monitor_chunks(chunk->next());

   } else {

     MonitorChunk* prev = monitor_chunks();

     while (prev->next() != chunk) prev = prev->next();

     prev->set_next(chunk->next());

   }

 }

 // JVM support.

 // Note: this function shouldn't block if it's called in

 // _thread_in_native_trans state (such as from

 // check_special_condition_for_native_trans()).

 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {

   if (has_last_Java_frame() && has_async_condition()) {

     // If we are at a polling page safepoint (not a poll return)

     // then we must defer async exception because live registers

     // will be clobbered by the exception path. Poll return is

     // ok because the call we a returning from already collides

     // with exception handling registers and so there is no issue.

     // (The exception handling path kills call result registers but

     //  this is ok since the exception kills the result anyway).

     if (is_at_poll_safepoint()) {

       // if the code we are returning to has deoptimized we must defer

       // the exception otherwise live registers get clobbered on the

       // exception path before deoptimization is able to retrieve them.

       //

       RegisterMap map(this, false);

       frame caller_fr = last_frame().sender(&map);

       assert(caller_fr.is_compiled_frame(), "what?");

       if (caller_fr.is_deoptimized_frame()) {

         if (TraceExceptions) {

           ResourceMark rm;

           tty->print_cr("deferred async exception at compiled safepoint");

         }

         return;

       }

     }

   }

   JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();

   if (condition == _no_async_condition) {

     // Conditions have changed since has_special_runtime_exit_condition()

     // was called:

     // - if we were here only because of an external suspend request,

     //   then that was taken care of above (or cancelled) so we are done

     // - if we were here because of another async request, then it has

     //   been cleared between the has_special_runtime_exit_condition()

     //   and now so again we are done

     return;

   }

   // Check for pending async. exception

   if (_pending_async_exception != NULL) {

     // Only overwrite an already pending exception, if it is not a threadDeath.

     if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {

       // We cannot call Exceptions::_throw(...) here because we cannot block

       set_pending_exception(_pending_async_exception, __FILE__, __LINE__);

       if (TraceExceptions) {

         ResourceMark rm;

         tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);

         if (has_last_Java_frame() ) {

           frame f = last_frame();

           tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());

         }

         tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());

       }

       _pending_async_exception = NULL;

       clear_has_async_exception();

     }

   }

   if (check_unsafe_error &&

       condition == _async_unsafe_access_error && !has_pending_exception()) {

     condition = _no_async_condition;  // done

     switch (thread_state()) {

     case _thread_in_vm:

       {

         JavaThread* THREAD = this;

         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");

       }

     case _thread_in_native:

       {

         ThreadInVMfromNative tiv(this);

         JavaThread* THREAD = this;

         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");

       }

     case _thread_in_Java:

       {

         ThreadInVMfromJava tiv(this);

         JavaThread* THREAD = this;

         THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");

       }

     default:

       ShouldNotReachHere();

     }

   }

   assert(condition == _no_async_condition || has_pending_exception() ||

          (!check_unsafe_error && condition == _async_unsafe_access_error),

          "must have handled the async condition, if no exception");

 }

 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {

   //

   // Check for pending external suspend. Internal suspend requests do

   // not use handle_special_runtime_exit_condition().

   // If JNIEnv proxies are allowed, don't self-suspend if the target

   // thread is not the current thread. In older versions of jdbx, jdbx

   // threads could call into the VM with another thread's JNIEnv so we

   // can be here operating on behalf of a suspended thread (4432884).

   bool do_self_suspend = is_external_suspend_with_lock();

   if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {

     //

     // Because thread is external suspended the safepoint code will count

     // thread as at a safepoint. This can be odd because we can be here

     // as _thread_in_Java which would normally transition to _thread_blocked

     // at a safepoint. We would like to mark the thread as _thread_blocked

     // before calling java_suspend_self like all other callers of it but

     // we must then observe proper safepoint protocol. (We can't leave

     // _thread_blocked with a safepoint in progress). However we can be

     // here as _thread_in_native_trans so we can't use a normal transition

     // constructor/destructor pair because they assert on that type of

     // transition. We could do something like:

     //

     // JavaThreadState state = thread_state();

     // set_thread_state(_thread_in_vm);

     // {

     //   ThreadBlockInVM tbivm(this);

     //   java_suspend_self()

     // }

     // set_thread_state(_thread_in_vm_trans);

     // if (safepoint) block;

     // set_thread_state(state);

     //

     // but that is pretty messy. Instead we just go with the way the

     // code has worked before and note that this is the only path to

     // java_suspend_self that doesn't put the thread in _thread_blocked

     // mode.

     frame_anchor()->make_walkable(this);

     java_suspend_self();

     // We might be here for reasons in addition to the self-suspend request

     // so check for other async requests.

   }

   if (check_asyncs) {

     check_and_handle_async_exceptions();

   }

 }

 void JavaThread::send_thread_stop(oop java_throwable)  {

   assert(Thread::current()->is_VM_thread(), "should be in the vm thread");

   assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");

   assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");

   // Do not throw asynchronous exceptions against the compiler thread

   // (the compiler thread should not be a Java thread -- fix in 1.4.2)

   if (is_Compiler_thread()) return;

   {

     // Actually throw the Throwable against the target Thread - however

     // only if there is no thread death exception installed already.

     if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {

       // If the topmost frame is a runtime stub, then we are calling into

       // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)

       // must deoptimize the caller before continuing, as the compiled  exception handler table

       // may not be valid

       if (has_last_Java_frame()) {

         frame f = last_frame();

         if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {

           // BiasedLocking needs an updated RegisterMap for the revoke monitors pass

           RegisterMap reg_map(this, UseBiasedLocking);

           frame compiled_frame = f.sender(&reg_map);

           if (compiled_frame.can_be_deoptimized()) {

             Deoptimization::deoptimize(this, compiled_frame, &reg_map);

           }

         }

       }

       // Set async. pending exception in thread.

       set_pending_async_exception(java_throwable);

       if (TraceExceptions) {

        ResourceMark rm;

        tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name());

       }

       // for AbortVMOnException flag

       NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name()));

     }

   }

   // Interrupt thread so it will wake up from a potential wait()

   Thread::interrupt(this);

 }

 // External suspension mechanism.

 //

 // Tell the VM to suspend a thread when ever it knows that it does not hold on

 // to any VM_locks and it is at a transition

 // Self-suspension will happen on the transition out of the vm.

 // Catch "this" coming in from JNIEnv pointers when the thread has been freed

 //

 // Guarantees on return:

 //   + Target thread will not execute any new bytecode (that's why we need to

 //     force a safepoint)

 //   + Target thread will not enter any new monitors

 //

 void JavaThread::java_suspend() {

   { MutexLocker mu(Threads_lock);

     if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {

        return;

     }

   }

   { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);

     if (!is_external_suspend()) {

       // a racing resume has cancelled us; bail out now

       return;

     }

     // suspend is done

     uint32_t debug_bits = 0;

     // Warning: is_ext_suspend_completed() may temporarily drop the

     // SR_lock to allow the thread to reach a stable thread state if

     // it is currently in a transient thread state.

     if (is_ext_suspend_completed(false /* !called_by_wait */,

                                  SuspendRetryDelay, &debug_bits) ) {

       return;

     }

   }

   VM_ForceSafepoint vm_suspend;

   VMThread::execute(&vm_suspend);

 }

 // Part II of external suspension.

 // A JavaThread self suspends when it detects a pending external suspend

 // request. This is usually on transitions. It is also done in places

 // where continuing to the next transition would surprise the caller,

 // e.g., monitor entry.

 //

 // Returns the number of times that the thread self-suspended.

 //

 // Note: DO NOT call java_suspend_self() when you just want to block current

 //       thread. java_suspend_self() is the second stage of cooperative

 //       suspension for external suspend requests and should only be used

 //       to complete an external suspend request.

 //

 int JavaThread::java_suspend_self() {

   int ret = 0;

   // we are in the process of exiting so don't suspend

   if (is_exiting()) {

      clear_external_suspend();

      return ret;

   }

   assert(_anchor.walkable() ||

     (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),

     "must have walkable stack");

   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);

   assert(!this->is_ext_suspended(),

     "a thread trying to self-suspend should not already be suspended");

   if (this->is_suspend_equivalent()) {

     // If we are self-suspending as a result of the lifting of a

     // suspend equivalent condition, then the suspend_equivalent

     // flag is not cleared until we set the ext_suspended flag so

     // that wait_for_ext_suspend_completion() returns consistent

     // results.

     this->clear_suspend_equivalent();

   }

   // A racing resume may have cancelled us before we grabbed SR_lock

   // above. Or another external suspend request could be waiting for us

   // by the time we return from SR_lock()->wait(). The thread

   // that requested the suspension may already be trying to walk our

   // stack and if we return now, we can change the stack out from under

   // it. This would be a "bad thing (TM)" and cause the stack walker

   // to crash. We stay self-suspended until there are no more pending

   // external suspend requests.

   while (is_external_suspend()) {

     ret++;

     this->set_ext_suspended();

     // _ext_suspended flag is cleared by java_resume()

     while (is_ext_suspended()) {

       this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);

     }

   }

   return ret;

 }

 #ifdef ASSERT

 // verify the JavaThread has not yet been published in the Threads::list, and

 // hence doesn't need protection from concurrent access at this stage

 void JavaThread::verify_not_published() {

   if (!Threads_lock->owned_by_self()) {

    MutexLockerEx ml(Threads_lock,  Mutex::_no_safepoint_check_flag);

    assert( !Threads::includes(this),

            "java thread shouldn't have been published yet!");

   }

   else {

    assert( !Threads::includes(this),

            "java thread shouldn't have been published yet!");

   }

 }

 #endif

 // Slow path when the native==>VM/Java barriers detect a safepoint is in

 // progress or when _suspend_flags is non-zero.

 // Current thread needs to self-suspend if there is a suspend request and/or

 // block if a safepoint is in progress.

 // Async exception ISN'T checked.

 // Note only the ThreadInVMfromNative transition can call this function

 // directly and when thread state is _thread_in_native_trans

 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {

   assert(thread->thread_state() == _thread_in_native_trans, "wrong state");

   JavaThread *curJT = JavaThread::current();

   bool do_self_suspend = thread->is_external_suspend();

   assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");

   // If JNIEnv proxies are allowed, don't self-suspend if the target

   // thread is not the current thread. In older versions of jdbx, jdbx

   // threads could call into the VM with another thread's JNIEnv so we

   // can be here operating on behalf of a suspended thread (4432884).

   if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {

     JavaThreadState state = thread->thread_state();

     // We mark this thread_blocked state as a suspend-equivalent so

     // that a caller to is_ext_suspend_completed() won't be confused.

     // The suspend-equivalent state is cleared by java_suspend_self().

     thread->set_suspend_equivalent();

     // If the safepoint code sees the _thread_in_native_trans state, it will

     // wait until the thread changes to other thread state. There is no

     // guarantee on how soon we can obtain the SR_lock and complete the

     // self-suspend request. It would be a bad idea to let safepoint wait for

     // too long. Temporarily change the state to _thread_blocked to

     // let the VM thread know that this thread is ready for GC. The problem

     // of changing thread state is that safepoint could happen just after

     // java_suspend_self() returns after being resumed, and VM thread will

     // see the _thread_blocked state. We must check for safepoint

     // after restoring the state and make sure we won't leave while a safepoint

     // is in progress.

     thread->set_thread_state(_thread_blocked);

     thread->java_suspend_self();

     thread->set_thread_state(state);

     // Make sure new state is seen by VM thread

     if (os::is_MP()) {

       if (UseMembar) {

         // Force a fence between the write above and read below

         OrderAccess::fence();

       } else {

         // Must use this rather than serialization page in particular on Windows

         InterfaceSupport::serialize_memory(thread);

       }

     }

   }

   if (SafepointSynchronize::do_call_back()) {

     // If we are safepointing, then block the caller which may not be

     // the same as the target thread (see above).

     SafepointSynchronize::block(curJT);

   }

   if (thread->is_deopt_suspend()) {

     thread->clear_deopt_suspend();

     RegisterMap map(thread, false);

     frame f = thread->last_frame();

     while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {

       f = f.sender(&map);

     }

     if (f.id() == thread->must_deopt_id()) {

       thread->clear_must_deopt_id();

       f.deoptimize(thread);

     } else {

       fatal("missed deoptimization!");

     }

   }

 }

 // Slow path when the native==>VM/Java barriers detect a safepoint is in

 // progress or when _suspend_flags is non-zero.

 // Current thread needs to self-suspend if there is a suspend request and/or

 // block if a safepoint is in progress.

 // Also check for pending async exception (not including unsafe access error).

 // Note only the native==>VM/Java barriers can call this function and when

 // thread state is _thread_in_native_trans.

 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {

   check_safepoint_and_suspend_for_native_trans(thread);

   if (thread->has_async_exception()) {

     // We are in _thread_in_native_trans state, don't handle unsafe

     // access error since that may block.

     thread->check_and_handle_async_exceptions(false);

   }

 }

 // We need to guarantee the Threads_lock here, since resumes are not

 // allowed during safepoint synchronization

 // Can only resume from an external suspension

 void JavaThread::java_resume() {

   assert_locked_or_safepoint(Threads_lock);

   // Sanity check: thread is gone, has started exiting or the thread

   // was not externally suspended.

   if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {

     return;

   }

   MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);

   clear_external_suspend();

   if (is_ext_suspended()) {

     clear_ext_suspended();

     SR_lock()->notify_all();

   }

 }

 void JavaThread::create_stack_guard_pages() {

   if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;

   address low_addr = stack_base() - stack_size();

   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();

   int allocate = os::allocate_stack_guard_pages();

   // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);

   if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {

     warning("Attempt to allocate stack guard pages failed.");

     return;

   }

   if (os::guard_memory((char *) low_addr, len)) {

     _stack_guard_state = stack_guard_enabled;

   } else {

     warning("Attempt to protect stack guard pages failed.");

     if (os::uncommit_memory((char *) low_addr, len)) {

       warning("Attempt to deallocate stack guard pages failed.");

     }

   }

 }

 void JavaThread::remove_stack_guard_pages() {

   if (_stack_guard_state == stack_guard_unused) return;

   address low_addr = stack_base() - stack_size();

   size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();

   if (os::allocate_stack_guard_pages()) {

     if (os::remove_stack_guard_pages((char *) low_addr, len)) {

       _stack_guard_state = stack_guard_unused;

     } else {

       warning("Attempt to deallocate stack guard pages failed.");

     }

   } else {

     if (_stack_guard_state == stack_guard_unused) return;

     if (os::unguard_memory((char *) low_addr, len)) {

       _stack_guard_state = stack_guard_unused;

     } else {

         warning("Attempt to unprotect stack guard pages failed.");

     }

   }

 }

 void JavaThread::enable_stack_yellow_zone() {

   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");

   assert(_stack_guard_state != stack_guard_enabled, "already enabled");

   // The base notation is from the stacks point of view, growing downward.

   // We need to adjust it to work correctly with guard_memory()

   address base = stack_yellow_zone_base() - stack_yellow_zone_size();

   guarantee(base < stack_base(),"Error calculating stack yellow zone");

   guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone");

   if (os::guard_memory((char *) base, stack_yellow_zone_size())) {

     _stack_guard_state = stack_guard_enabled;

   } else {

     warning("Attempt to guard stack yellow zone failed.");

   }

   enable_register_stack_guard();

 }

 void JavaThread::disable_stack_yellow_zone() {

   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");

   assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");

   // Simply return if called for a thread that does not use guard pages.

   if (_stack_guard_state == stack_guard_unused) return;

   // The base notation is from the stacks point of view, growing downward.

   // We need to adjust it to work correctly with guard_memory()

   address base = stack_yellow_zone_base() - stack_yellow_zone_size();

   if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {

     _stack_guard_state = stack_guard_yellow_disabled;

   } else {

     warning("Attempt to unguard stack yellow zone failed.");

   }

   disable_register_stack_guard();

 }

 void JavaThread::enable_stack_red_zone() {

   // The base notation is from the stacks point of view, growing downward.

   // We need to adjust it to work correctly with guard_memory()

   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");

   address base = stack_red_zone_base() - stack_red_zone_size();

   guarantee(base < stack_base(),"Error calculating stack red zone");

   guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone");

   if(!os::guard_memory((char *) base, stack_red_zone_size())) {

     warning("Attempt to guard stack red zone failed.");

   }

 }

 void JavaThread::disable_stack_red_zone() {

   // The base notation is from the stacks point of view, growing downward.

   // We need to adjust it to work correctly with guard_memory()

   assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");

   address base = stack_red_zone_base() - stack_red_zone_size();

   if (!os::unguard_memory((char *)base, stack_red_zone_size())) {

     warning("Attempt to unguard stack red zone failed.");

   }

 }

 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {

   // ignore is there is no stack

   if (!has_last_Java_frame()) return;

   // traverse the stack frames. Starts from top frame.

   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {

     frame* fr = fst.current();

     f(fr, fst.register_map());

   }

 }

 #ifndef PRODUCT

 // Deoptimization

 // Function for testing deoptimization

 void JavaThread::deoptimize() {

   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass

   StackFrameStream fst(this, UseBiasedLocking);

   bool deopt = false;           // Dump stack only if a deopt actually happens.

   bool only_at = strlen(DeoptimizeOnlyAt) > 0;

   // Iterate over all frames in the thread and deoptimize

   for(; !fst.is_done(); fst.next()) {

     if(fst.current()->can_be_deoptimized()) {

       if (only_at) {

         // Deoptimize only at particular bcis.  DeoptimizeOnlyAt

         // consists of comma or carriage return separated numbers so

         // search for the current bci in that string.

         address pc = fst.current()->pc();

         nmethod* nm =  (nmethod*) fst.current()->cb();

         ScopeDesc* sd = nm->scope_desc_at( pc);

         char buffer[8];

         jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());

         size_t len = strlen(buffer);

         const char * found = strstr(DeoptimizeOnlyAt, buffer);

         while (found != NULL) {

           if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&

               (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {

             // Check that the bci found is bracketed by terminators.

             break;

           }

           found = strstr(found + 1, buffer);

         }

         if (!found) {

           continue;

         }

       }

       if (DebugDeoptimization && !deopt) {

         deopt = true; // One-time only print before deopt

         tty->print_cr("[BEFORE Deoptimization]");

         trace_frames();

         trace_stack();

       }

       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());

     }

   }

   if (DebugDeoptimization && deopt) {

     tty->print_cr("[AFTER Deoptimization]");

     trace_frames();

   }

 }

 // Make zombies

 void JavaThread::make_zombies() {

   for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {

     if (fst.current()->can_be_deoptimized()) {

       // it is a Java nmethod

       nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());

       nm->make_not_entrant();

     }

   }

 }

 #endif // PRODUCT

 void JavaThread::deoptimized_wrt_marked_nmethods() {

   if (!has_last_Java_frame()) return;

   // BiasedLocking needs an updated RegisterMap for the revoke monitors pass

   StackFrameStream fst(this, UseBiasedLocking);

   for(; !fst.is_done(); fst.next()) {

     if (fst.current()->should_be_deoptimized()) {

       Deoptimization::deoptimize(this, *fst.current(), fst.register_map());

     }

   }

 }

 // GC support

 static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); }

 void JavaThread::gc_epilogue() {

   frames_do(frame_gc_epilogue);

 }

 static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); }

 void JavaThread::gc_prologue() {

   frames_do(frame_gc_prologue);

 }

 // If the caller is a NamedThread, then remember, in the current scope,

 // the given JavaThread in its _processed_thread field.

 class RememberProcessedThread: public StackObj {

   NamedThread* _cur_thr;

 public:

   RememberProcessedThread(JavaThread* jthr) {

     Thread* thread = Thread::current();

     if (thread->is_Named_thread()) {

       _cur_thr = (NamedThread *)thread;

       _cur_thr->set_processed_thread(jthr);

     } else {

       _cur_thr = NULL;

     }

   }

   ~RememberProcessedThread() {

     if (_cur_thr) {

       _cur_thr->set_processed_thread(NULL);

     }

   }

 };

 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {

   // Verify that the deferred card marks have been flushed.

   assert(deferred_card_mark().is_empty(), "Should be empty during GC");

   // The ThreadProfiler oops_do is done from FlatProfiler::oops_do

   // since there may be more than one thread using each ThreadProfiler.

   // Traverse the GCHandles

   Thread::oops_do(f, cf);

   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||

           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");

   if (has_last_Java_frame()) {

     // Record JavaThread to GC thread

     RememberProcessedThread rpt(this);

     // Traverse the privileged stack

     if (_privileged_stack_top != NULL) {

       _privileged_stack_top->oops_do(f);

     }

     // traverse the registered growable array

     if (_array_for_gc != NULL) {

       for (int index = 0; index < _array_for_gc->length(); index++) {

         f->do_oop(_array_for_gc->adr_at(index));

       }

     }

     // Traverse the monitor chunks

     for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {

       chunk->oops_do(f);

     }

     // Traverse the execution stack

     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {

       fst.current()->oops_do(f, cf, fst.register_map());

     }

   }

   // callee_target is never live across a gc point so NULL it here should

   // it still contain a methdOop.

   set_callee_target(NULL);

   assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");

   // If we have deferred set_locals there might be oops waiting to be

   // written

   GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();

   if (list != NULL) {

     for (int i = 0; i < list->length(); i++) {

       list->at(i)->oops_do(f);

     }

   }

   // Traverse instance variables at the end since the GC may be moving things

   // around using this function

   f->do_oop((oop*) &_threadObj);

   f->do_oop((oop*) &_vm_result);

   f->do_oop((oop*) &_vm_result_2);

   f->do_oop((oop*) &_exception_oop);

   f->do_oop((oop*) &_pending_async_exception);

   if (jvmti_thread_state() != NULL) {

     jvmti_thread_state()->oops_do(f);

   }

 }

 void JavaThread::nmethods_do(CodeBlobClosure* cf) {

   Thread::nmethods_do(cf);  // (super method is a no-op)

   assert( (!has_last_Java_frame() && java_call_counter() == 0) ||

           (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");

   if (has_last_Java_frame()) {

     // Traverse the execution stack

     for(StackFrameStream fst(this); !fst.is_done(); fst.next()) {

       fst.current()->nmethods_do(cf);

     }

   }

 }

 // Printing

 const char* _get_thread_state_name(JavaThreadState _thread_state) {

   switch (_thread_state) {

   case _thread_uninitialized:     return "_thread_uninitialized";

   case _thread_new:               return "_thread_new";

   case _thread_new_trans:         return "_thread_new_trans";

   case _thread_in_native:         return "_thread_in_native";

   case _thread_in_native_trans:   return "_thread_in_native_trans";

   case _thread_in_vm:             return "_thread_in_vm";

   case _thread_in_vm_trans:       return "_thread_in_vm_trans";

   case _thread_in_Java:           return "_thread_in_Java";

   case _thread_in_Java_trans:     return "_thread_in_Java_trans";

   case _thread_blocked:           return "_thread_blocked";

   case _thread_blocked_trans:     return "_thread_blocked_trans";

   default:                        return "unknown thread state";

   }

 }

 #ifndef PRODUCT

 void JavaThread::print_thread_state_on(outputStream *st) const {

   st->print_cr("   JavaThread state: %s", _get_thread_state_name(_thread_state));

 };

 void JavaThread::print_thread_state() const {

   print_thread_state_on(tty);

 };

 #endif // PRODUCT

 // Called by Threads::print() for VM_PrintThreads operation

 void JavaThread::print_on(outputStream *st) const {

   st->print("\"%s\" ", get_thread_name());

   oop thread_oop = threadObj();

   if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop))  st->print("daemon ");

   Thread::print_on(st);

   // print guess for valid stack memory region (assume 4K pages); helps lock debugging

   st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));

   if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) {

     st->print_cr("   java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));

   }

 #ifndef PRODUCT

   print_thread_state_on(st);

   _safepoint_state->print_on(st);

 #endif // PRODUCT